不同分子量聚乙烯吡咯烷酮对四氢呋喃水合物形成及生长的影响

聚乙烯吡咯烷酮(以下简称PVP)作为一种抑制能力较强、应用较成熟的水合物动力学抑制剂(以下简称KHIs),一直是国内外学者关注和研究的焦点,但对于不同分子量PVP对水合物形成的影响情况还存在着争议。为此,在常压、变温条件下进行了四氢呋喃(以下简称THF)水合物形成模拟实验,研究了相同加量条件下、不同分子量的PVP对THF水合物形成及生长的影响,并从宏观现象、介观结构和微观机制3个层面对影响机理进行了分析和探讨。结果表明:(1)对于THF水合物的形成,PVP的抑制能力随分子量的增大逐渐增强;(2)对于THF水合物的生长,PVP分子量介于8 000~58 000时,抑制效果较接近且相对较弱,但抑制作用稳定,PVP分子量介于270 000~1 500 000时,在THF水合物生长初始阶段PVP的抑制效果较好,但整个实验过程THF水合物形成的平均速率相对较快,且PVP分子量越大这一现象越明显;(3)PVP的存在增强了THF水合物聚集体的聚集强度。结论认为,该研究成果对于KHIs的研发和实际应用均具有较重要的参考价值。

Effects of polyvinylpyrrolidone with different molecular weights on the formation and growth of tetrahydrofuran hydrate

As a kind of well-performed and widely-used kinetic hydrate inhibitor (KHIs), polyvinylpyrrolidone (PVP) is attractive to many scholars in China and abroad. However, it is still controversial on the hydrate inhibition of PVPs with different molecular weights. In this paper, the formation of tetrahydrofuran (THF) hydrate was experimentally simulated under normal pressure and changing temperature to identify the effects of PVPs with different molecular weights at the same dosage on the formation and growth of THF hydrate. Besides, the influence mechanisms were discussed from three aspects, i.e., macroscopic phenomenon, mesoscopic structure and microscopic mechanism. The following results were obtained. First, the inhibition of PVP on the formation of THF hydrate increases gradually with the increase of molecular weight. Second, PVPs with a molecular weight of 8 000-58 000 have similar weak but stable inhabitation on the growth of THF hydrate. PVPs with a molecular weight of 270 000-1 500 000 demonstrate good inhibition on the growth of THF hydrate at the initial stage of hydrate growth, but the average formation rate of THF hydrate is high in the whole process of the experiment. This phenomenon is more obvious at higher molecular weight. Third, the existence of PVP enhances the agglomeration intensity of THF hydrate agglomerates. The research results can be used as valuable reference for the development and application of KHIs.